Group of steam turbines with bleeder steam feed water preheater



y 1960 M. ZIMMERMANN 2,938,350

GROUP OF STEAM TURBINES WITH BLEEDER STEAM FEED WATER PREHEATER Filed Sept. 14, 1956 INVENTOR. /7ax ZLH? mermem BY MJWAPDM GROUP OF STEAM TURBINES WITH BLEEDER STEAM FEED WATER PREHEATER Max Zimmermann, Riniken, near Brugg, Switzerland, assignor to Aktiengesellschaft Brown, Boveri & Cle, Baden, Switzerland, a joint-stock company Filed Sept. 14, 1956, Ser. No. 609,858

Claims priority, application Switzerland Sept. 27, 1955 1 Claim. (Cl. 60-67) The present invention relates to steam turbines and in particular to an improved arrangement for the feedwater preheater components which are heated by bleeder steam.

In the past, the feed-water preheaters, heated by bleeder steam irom the turbine have usually been located externally of the same and connected with the turbine by means of more or less long pipe lines with the tapping points for the bleeder steam on the turbine. It has also been suggested that a low pressure preheater be installed in the exhaust steam pipe of the turbine.

The present invention relates to a group of steam turbines with bleeder steam feed-water preheaters and is characterized in that at least one of the feed-water preheaters is located in the low pressure casing of the turbine. More particularly, a feature of the invention is that the teed-water preheater for a low pressure stage of the turbine is subdivided into two preheater sections operating in parallel and arranged vertically within the outer casing of the turbine and adjacent to and at opposite sides of the turbine inner casing for that low pressure stage.

The accompanying drawing illustrates an embodiment of the invention as applied to the low pressure casing of a multicylinder large turbine with a triple-exhaust low pressure part. In the drawings, Fig. 1 is a vertical transverse section through the casing on line 1-1 of Fig. 2, and Fig. 2 is a horizontal section through an axial plane l1II on Fig. 1.

With reference now to the'drawings, the low pressure casing 1 of the turbine includes, for example, the interior casings 2 and 3 of the low pressure part of a tripleexhaust turbine, as well as the low pressure feed-water preheaters 4A, 4B and 5A, 5B of the two lowest values of the bleeder steam pressure. The preheaters 4A, 4B are associated with the penultimate pressure value and the two preheaters 5A, 5B are associated with the lowest pressure value. The preheaters 4A, 4B are parallelly connected and the bleeder steam lines thereto are indicated at 6A, 6B. In a similar manner, the bleeder steam lines to the parallelly connected preheaters 5A, 5B are indicated at 7A, 7B. The feed-water connections to the preheaters 4A, 4B and 5A, 5B and United States Patent 0 ice which place the same for operation in parallel are indicated schematically in Fig. 2 by the interrupted lines 8, and valves 9 may be placed in these lines if desired for control purposes. The preheaters work in pairs connected upstream side-by-side. It will be noted that the preheater sections 4A, 4B and 5A, 5B are disposed vertically and adjacent opposite sides of the hirer casings 2, 3 respectively.

The arrangement of the preheaters in the low pressure casing of the turbine offers a great savings in space in comparison to the known preheater locating arrangements. Moreover, one is able to avoid the difliculties otherwise present in known arrangements created as a result of large low-pressure power lead-in from the low pressure casing of the turbine. The power lead-in is short and hence the cost of material therefor is insignificant. Moreover, it is not necessary to construct them in a massive sturdy manner since both they and the preheaters are disposed entirely in the vacuum. The division of the preheater of a specific pressure value or grade into two symmetrical part preheaters with like power lead-in lines is advantageous since it requires much less space than would be taken up by a single unit preheater of like capacity. Moreover, in the event of a pipe fault, one of the preheaters can be shut oii upstream while the group of turbines itselt need not be closed; in such a case, the entire quantity of feed water flows through the other preheater part. In comparison with the known, horizontally constructed preheaters in the exhaust steam pipe of the turbine, the entire device according to the present invention offers the advantage that any elevation of the foundation and all other difficulties connected therewith, e.g. concerning accessibility of the preheaters, are eliminated.

I claim:

A steam turbine unit having spaced outer and inner casings forming a chamber therebetween, said chamber being at sub-atmospheric pressure and receiving steam discharging from said turbine, preheater means consisting of two symmetrical preheater sections operating in parallel, said sections being disposed vertically and adjacent to and at opposite sides of said inner casing between and spaced from boththe latter and said outer casing, and steam connection conduits communicating with the interior of said inner casing at locations where the turbine steam pressure is substantially equal to said subatmospheric pressure and conveying said sub-atmospheric pressure steam to the interior of said preheater sections.

References Cited in the file of this patent UNITED STATES PATENTS 1,342,841 Baumann June 8, 1920 1,465,095 Richardson Aug. 14, 1923 1,573,851 Nytfenegger Feb. 23, 1926 FOREIGN PATENTS 237,072 Switzerland July 16, 1945 

